Original Research Article DOI: 10.18231/2394-2126.2017.0103 A cadaveric study of Gastrocnemius muscle from point of view of entrapment syndromes Shinde Amol Ashok1, Dinesh K. Patel2,*, Varshaly K. Bharambe3 1,2Assistant Professor, 3Professor, Dept. of Anatomy, Dr. DY Patil Medical College, Pune, Maharashtra *Corresponding Author: Email: [email protected] Abstract Introduction: Gastrocnemius has a medial and lateral belly. It joins with soleus to get inserted as the Achilles tendon. Accessory heads of gastrocnemius can give rise to popliteal artery entrapment syndromes. Materials and Method: 60 formalin embalmed lower limbs mere meticulously dissected to see for any variation in number of heads and nerve supply of Gastrocnemius. Observations: 15% limbs showed accessory heads of gastrocnemius. 8.34% showed 4 heads and 6.66% showed 3 heads. Length of Achilles tendon in limbs with variation ranged from 6.1 cm to 12.8 cm. Conclusion: Knowledge of accessory heads of gastrocnemius will help the radiologist during imaging studies in cases of polpliteal entrapment syndromes and neurovascular compression. Keywords: Gastrocnemius tertius, Accessory head of gastrocnemius, Popliteal artery entrapment syndrome, Calf injury, Additional heads of gastrocnemius. Received: 10th August, 2017 Accepted: 10th October, 2017 Introduction vernier caliper and measuring tape as applicable. The calf is made of bipennate muscle Relation of the popliteal artery to the additional heads gastrocnemius and multipennate muscle soleus. of gastrocnemius was noted. Gastrocnemius has a medial head known as capute mediale and a lateral head known as capute laterale.(1) Result Medial head takes origin from posterior surface of Additional head of gastrocnemius was seen in 9 femur above medial condyle and lateral head arises (15%) lower limbs. 3 cadavers showed bilateral above the lateral condyle. Both heads of gastrocnemius variation(10%). 2 right sided and one left sided lower fuse to form a single belly which together with soleus limb showed unilateral variation. 4 heads of forms the Achilles tendon. The Achilles tendon gets gastrocnemius (Fig. 3) were seen in 5 (8.34%) limbs.2 inserted on the dorsal surface of calcaneum. cadavers showed 4 heads bilaterally. One right limb The word gastrocnemius is derived from greek demonstrated 4 headed gastrocnemius. 3 heads of words gastro and kneme meaning stomach and leg gastrocnemius (Fig. 1and 2) were seen in 4 (6.66%) respectively.The bulging of the calf mimics the bulging limbs. One cadaver showed bilateral 3 heads of of stomach,so it is also called ‘stomach of leg’. (2) gastrocnemius. One right and one left side limb showed The tibial nerve supplies the gastrocnemius muscle. 3 heads of gastrocnemius. All the heads of It is strong plantar flexor of foot. Soleus acts to initiate gastrocnemius were supplied by tibial nerve. No walking while gastrocnemius is muscle used in running. variation in course of sural nerve was noted. The Heads of gastrocnemius form the inferolateral and popliteal artery was seen passing between the accessory inferomedial boundaries of popliteal fossa. medial head and normal medial head of gastrocnemius Close proximity to Tibial nerve and popliteal in 2 cadavers (Fig. 3). vessels in popliteal fossa makes any variant anatomy of A single belly was formed by joining of all heads gastrocnemius as a differential diagnosis in of gastrocnemius. This muscle belly joined with belly neurovascular compressions and entrapment of soleus to form the Achilles tendon, which inserted on syndromes.(3) posterior surface of calcaneum. Length of the heads of gastrocnemius before forming common tendon and Materials and Method length of Achilles tendon is tabulated in Table 1. Meticulous dissection of 60 formalin embalmed Maximum length seen for medial and lateral bellies are lower limbs was done. Any variation in number of 7.5 cm and 9 cm respectively Length of Achilles tendon heads, origin, insertion and nerve supply of of limbs with additional heads of gastrocnemius ranged gastrocnemius muscle is noted. Length of the heads of from 6.1 cm to 12.8 cm. gastrocnemius and Achilles tendon are measured with Indian Journal of Clinical Anatomy and Physiology, October-December, 2017;4(4):407-411 407 Shinde Amol Ashok et al. A cadaveric study of Gastrocnemius muscle from point of view of entrapment syndromes Fig. 1: Showing three headed gastrocnemius: A – Medial head of gastrocnemius, B – Additional medial head of gastrocnemius, C – Lateral head of gastrocnemius, D – Additional lateral head of gastrocnemius, T – Achilles tendon, S – Soleus and N – Tibial nerve Fig. 2: Showing three headed gastrocnemius: A – Medial head of gastrocnemius, B – Additional medial head of gastrocnemius, C – Lateral head of gastrocnemius, D – Additional lateral head of gastrocnemius and T – Achilles tendon Fig. 3: Four headed gastrocnemius: A – Medial head of gastrocnemius, B – Additional medial head of gastrocnemius, C – Lateral head of gastrocnemius, D – Additional lateral head of gastrocnemius and N – Tibial nerve Table 1: Showing lengths of bellies of gastrocnemius and Achilles tendon in limbs with accessory bellies of gastrocnemius S. N. Side Number of bellies Muscle length Tendon length of Gastrocnemius (cm) medial to lateral (cm) 1 Right 4 5.2 6.1 5.9 7.4 8.6 2 Left 4 5.6 6.5 5.4 6.9 7.1 3 Right 4 7.5 12.6 Indian Journal of Clinical Anatomy and Physiology, October-December, 2017;4(4):407-411 408 Shinde Amol Ashok et al. A cadaveric study of Gastrocnemius muscle from point of view of entrapment syndromes 7.1 8.3 9.0 4 Left 4 6.8 12.8 7.1 9.2 9.4 5 Right 4 6.7 12.5 6.9 8.8 9.3 6 Right 4 5.9 11.9 6.2 8.4 7 Right 3 5.6 7.2 6.1 7.5 8 Right 3 7.1 12.5 7.2 7.9 9 Left 3 7.3 12.8 7.7 8.3 Discussion In a study of gastrocnemius in Nigerian population, Embryological reasoning: Gastrocnemius muscle Ashaolu et al(3) give a 51.7% incidence of four headed embryologically originates from the calcaneum gastrocnemius and 13.3% incidence for 3 headed blastomere and then it migrates upwards by ascending gastrocnemius. These figures are more than our study towards the inferior epiphysis of femur. Before where we got incidence of four-headed gastrocnemius termination on femur it splits into medial and lateral as 8.33% and three headed gastrocnemius as 6.66%. bellies. Any variant mode of embryological migration Knowledge of such variations will help during popliteal and termination may result as variation in number of nerve blocks and autografting of gastrocnemius muscle. bellies and attachments.(3) Shinde et al(6) in a study of soleus muscle report Gastrocnemius is the superficial calf muscle. It 8% cases of accessory head of soleus. One limb showed originates as medial and lateral heads. The medial head three-heads of gastrocnemius with an accessory head of is more commonly injured. Medial head of soleus. This condition is known as gastrocnemius gastrocnemius sprain is also called ‘Tennis leg’ as it is tertius. Coexistence of gastrocnemius tertius and frequently seen in tennis players. Risk of strain of accessory soleus is considered a rare variation. gastrocnemius is more as it crosses two joints (knee and Yildirim et al(7) report a case of bilateral ankle) and has type two fast acting muscle fibers. Strain gastrocnemius terius with unilateral accessory head of of gastrocnemius is called ‘coup de fouet’ or snap of a soleus. Accessory head of gastrocnemius can lead to whip.(4) entrapment syndromes in popliteal fossa. Decrease in Sookur et al(5) in a study of variations of muscles of pulse of distal arteries on passive dorsiflexion suggests lower limb state that variations of medial and lateral popliteal artery entrapment, while pain and tenderness heads of gastrocnemius are due to anomalous origins in popliteal fossa points towards nerve compression in and accessory slips. Medial and lateral heads of the popliteal fossa. gastrocnemius take origin from posterior surface of Calf injuries are one of the most common muscle femur, above the condyles and from the capsule of the injuries of leg. Gastrocnemius acts to flex the leg at knee joint. Additional medial head may arise from knee joint and plantar flex the foot at ankle joint. intercondylar notch instead of medial condyle. Gastrocnemius injury is considered high risk because it Additional slips may arise from intercondylar notch and crosses two main joints, the knee and ankle. Calf pass between popliteal artery and vein to get inserted injuries occur with strenuous exercise and also on into medial head. Lateral head may have a more medial innocuous movements in middle aged people with origin on posterior surface of femur, but lateral to sedentary lifestyle. Differential diagnosis for calf injury politeal artery. Additional slips may pass anterolatral to are gastrocnemius tear, thrombophlebitis, soleus tear, popliteal vessels and insert in the lateral head. Achilles tendon rupture, and posterior compartment syndrome. Pain in the medial head of gastrocnemius Indian Journal of Clinical Anatomy and Physiology, October-December, 2017;4(4):407-411 409 Shinde Amol Ashok et al. A cadaveric study of Gastrocnemius muscle from point of view of entrapment syndromes just above the musculotendinous junction with palpable reported. Intermittent claudication on physical activity tenderness are clinical signs to diagnose gastrocnemius is seen in young adults. Soldiers and athletes are more tear.(8) likely to succumb to popliteal artery entrapment A case report of four headed gastrocnemius was syndromes as their muscles are well toned and given by Rodrigues et al.(9) They describe the medial enlarged. Any accessory muscle forming the boundary head of gastrocnemius splitting into three heads. The of popliteal fossa may lead to compression of the artery.